Dubicka Zofia, Bojanowski Maciej J, Bijma Jelle, Bickmeyer Ulf
Ecological Chemistry, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, 27-570, Germany.
University of Warsaw, Warsaw, 02-089, Poland.
Heliyon. 2023 Jul 17;9(7):e18331. doi: 10.1016/j.heliyon.2023.e18331. eCollection 2023 Jul.
Calcium carbonate minerals produced by marine organisms play a central role in the global carbon cycle and carbonate sedimentation, which influence the climate by regulating atmospheric CO levels. Foraminifera are important marine single-celled organisms that have produced calcite shells for over 300 million years. Here, we present new observations promoting our understanding for foraminiferal biocalcification by studying . We integrated in vivo confocal autofluorescence and dye fluorescence imaging with elemental analysis of the cell supporting the concept that the calcite shells of foraminifera are produced via deposition of intracellularly formed Mg-rich amorphous calcium carbonate (Mg-ACC) particles that transform into a stable mineral phase. This process is likely accompanied by the activity of endosymbiotic microalgae and seawater-derived endocytic vesicles that provide calcification substrates such as DIC, Ca, and Mg. The final transformation of semi-liquid amorphous nanoparticles into a crystalline shell was associated with Mg liberation.
海洋生物产生的碳酸钙矿物在全球碳循环和碳酸盐沉积中起着核心作用，而全球碳循环和碳酸盐沉积通过调节大气中的二氧化碳水平来影响气候。有孔虫是重要的海洋单细胞生物，它们制造方解石外壳的历史已超过3亿年。在此，我们通过研究提出了新的观察结果，增进了我们对有孔虫生物矿化作用的理解。我们将体内共聚焦自发荧光和染料荧光成像与细胞的元素分析相结合，支持了这样一种观点，即有孔虫的方解石外壳是通过细胞内形成的富含镁的无定形碳酸钙（Mg-ACC）颗粒沉积而产生的，这些颗粒会转变为稳定的矿物相。这个过程可能伴随着内共生微藻和源自海水的内吞小泡的活动，它们提供钙化底物，如溶解无机碳（DIC）、钙和镁。半液体无定形纳米颗粒最终转变为晶体外壳与镁的释放有关。
